In less invasive surgical procedures, such as endoscopic or arthroscopic procedures, cannulas are inserted into portals to create a tunnel through which a surgical site can be accessed by a variety of surgical instruments. Some styles of cannula, such as flexible cannulas, including “button” style cannulas, solve many of the problems typically associated with rigid cannulas. Flexible button style cannulas, for example, consist of a flexible tube having flexible flanges at either end. Once these cannulas are inserted, the flanges hold the cannula in place and protect surrounding soft tissues from being damaged by the insertion, movement, and removal of instruments inserted into the body via the cannula. The flexibility of these cannulas allows for one or more flanges, when present as in a button style cannula, to lie flat against the inner tissues inside of the portal for the inner flange and against the skin for the outer flange. This keeps the inner portion of the cannula out of the way of surgical instruments, permitting unobstructed manipulation at the surgical site. Further, the flexibility of these cannulas makes manipulation of instruments at the surgical site easier, for example, by providing “give” when a surgeon has to lean or lever an instrument against the cannula when reaching at a difficult angle.
While these flexible button style cannulas offer significant advantages, they can be difficult to insert. Typically, this style of cannula is inserted by folding the interior flange, making a “taco” or “U” shape, and then using a curved hemostat to push the cannula into an existing portal. Friction from the portal often causes the cannula to slip out of the clamp, resulting in the cannula dislodging, and needing to re-start the insertion process. Successful insertion of the cannula requires that a surgeon identify the exact path or track of the original portal in as few attempts as possible, which can be difficult. Each unsuccessful attempt at insertion may cause additional subcutaneous and intramuscular tracks to develop, increasing the risk of water extravasation and damaging surrounding tissue. Extra attempts at insertion also increase surgical time and surgeon frustration. Further, multiple cannulas may be required if a cannula is damaged, dropped, or contaminated. The use of hemostats for insertion also presents some challenges. First, the portal skin incision needs to be longer to accommodate the increased bulk of the hemostat handles, which widen as they approach the finger loops. Second, because the portals used in less invasive surgical procedures are quite small, often on the scale of a few millimeters, it can be very difficult to open the clamped hemostat to release the cannula and place it in the portal. This becomes more problematic as the cannula increases in length. Finally, once the cannula is released from the hemostat clamp, the hemostat, which now located between the cannula and the perimeter of the portal, must be withdrawn from the portal without dislodging the cannula that is filling the portal. It can be difficult to withdraw the hemostat without dislodging the cannula.
In some cases, sutures may be passed through the cannula, and these sutures may be drawn or pulled into and through a first portal by a device that has an eyelet, clamp, or other means for securing the sutures to the device. This device is inserted through the joint via a second portal. The sutures are then pulled through the second portal, and can be tensioned, pulled, and used to manipulate the interior flange and position the cannula within the first portal. While this might be less traumatic to the soft tissue of the first portal and may result in easier placement of the cannula, it increases the minimum number of incisions/portals required to perform a procedure (at least 3 portals—1 portal for visualization, 1 portal for access with the clamp/eyelet device, 1 portal for cannula insertion, as opposed to 2 portals—1 portal for visualization, 1 portal for instrument access), increases surgical time by having to pass the suture in the cannula and making the extra portal that may otherwise be unnecessary, and increases cost because of the extra suture material required and increased surgical time.
In order to maximize the benefits flexible cannulas offer for both surgeons and patients, there exists a need for a more consistent, reliable, and less traumatic way to insert flexible cannulas.